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DIY: Do It Yourself Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

U have to find the leak u r letting air into the system which causes overheating (boiling water idea) check the air relief valve right above reservoir. Again find the leak u can damage the heads if it gets to hot

Thanks John, looks like I'll be busy this weekend Boys.
Do you guys know of any auto parts shops that will have any of these hoses in hand???

I tried my thermostat change today, my bolts were very corroded and one the bolts head broke off when I was trying to remove it so its stuck in.

see pic attached of which one it is.

some questions :

1. How can I remove it?
2. What if I just leave it in there and replace my thermostat and tighthen the other 2 bolts, if I put rtv sealant as well. Will I be ok or will it leak?
3. how much do garages charge to drill out bolts etc?

Hello Guys. I'm hoping someone can provide some quick advice . I just replaced my thermostat in my 2004 E46 convertible, automatic. Everything reassembled, but after refilling the coolant and checking for leaks I found one, on the blue radiator plug under the expansion tank. I tightened the blue plug, just so it's snug.. However, the leak is coming from the black nut which the blue plug sits within. The nut looks like something meant to be tightened, but its not happy when I put a crescent wrench on it. It's a drip every 5 seconds or so at idle. Can anyone recommend a way to stop the leak? Some sort of goo I can put around the nut? Help! I attached a photo for clarification.

Hello Guys. I'm hoping someone can provide some quick advice . I just replaced my thermostat in my 2004 E46 convertible, automatic. Everything reassembled, but after refilling the coolant and checking for leaks I found one, on the blue radiator plug under the expansion tank. I tightened the blue plug, just so it's snug.. However, the leak is coming from the black nut which the blue plug sits within. The nut looks like something meant to be tightened, but its not happy when I put a crescent wrench on it. It's a drip every 5 seconds or so at idle. Can anyone recommend a way to stop the leak? Some sort of goo I can put around the nut? Help! I attached a photo for clarification.

hmm mine looks a bit different i think, I don't believe you are supposed to tighten anything down there. Are you sure the leak is not from the expansion tank - connector below that comes from?

Edit: I believe they're different because yours is automatic and mine is manual

I just replaced my thermostat today. It was stuck open. Also, the gasket had deteriorated along the bottom. Here's the bleeding procedure I used and everything looks good. Make sure to check your coolant level when your engine has cooled after your next drive.

Coolant Bleeding procedure.
Open sealing cap. Set heater control to maximum temperature. Set blower to low level. This opens the heating valves and sets the auxiliary water pump in operation. Run engine and briefly press accelerator pedal three to four times (approx. 4500 to 5000 rpm) to flush engine cooling circuit. In doing so, do not run engine for longer than approx. 30 seconds; otherwise coolant will heat up and expand. If the coolant level drops in the expansion tank during this operation, top up expansion tank with coolant up to edge. Screw on sealing cap and warm up engine until thermostat opens.http://forum.e46fanatics.com/showpos...6&postcount=35

This is WRONG! Running the engine is not required or recommended to bleed the system properly! Do the heater thing and remove the bleeder screw. Pour the coolant into the tank until the fluid rises to the screw hole. Stop and wait as the air majically comes out all by itself! Pour again until the fluid at the screw hole stops dropping. If the car is on the wheels you might have to add more, if it's on a couple of 2X like I do to get underneath, it may actually over fill some. Start and drive through full temp, stop and cool, then check the level in the tank. The torque is 10 lbft. The only reason to use goop is if the block mating surface is F'd up. Otherwise no-no. If bolts are broken, it's because some a-hole tightened them too tight.

First time BMW (05/325ci) automatic) owner the car is over heating I first thought it was because the electric fan was not working. I just notice that the car but when I checked it the lower hose to the radiator was not hot but the top one was boiling. Does that mean that the thermostat is not working and should be replaced? Coolant level is good.
thanks for any info that you can provide.

Thanks to OP for a great DIY, although I have a question, is there a thermostat housing for M54B25 engines that will run the engine cooler i.e. open the thermostat earlier than 93F ????

There was a discussion a lot of times regarding this time, and the general conclusion is that the current factory thermostat are optimized from the factory to provide the best combination among cooling and fuel efficiency. The ECU can and will open the thermostat earlier than its mechanical threshold if certain conditions are met (temperature, load, rpm) so there's no point in my opinion to mess up with other types of thermostats.

There was a discussion a lot of times regarding this time, and the general conclusion is that the current factory thermostat are optimized from the factory to provide the best combination among cooling and fuel efficiency. The ECU can and will open the thermostat earlier than its mechanical threshold if certain conditions are met (temperature, load, rpm) so there's no point in my opinion to mess up with other types of thermostats.

Are you facing a problem related with temperatures?

Thanks paraklas, I am not having any problems, just had a leak, so I thought I would try replacing the thermostat altogether with a new one and see if there is any better available. I guess old school plastic housing is the way to go from what you are saying.

Another question though, I am not sure when the thermostat housing was changed, if it is leaking, is it advisable to change the entire thermostat housing or just the gasket?

I agree with the RTV idea. I installed a new thermostat when I did a cooling system rebuild, torqued the thermostat to 10NM, etc., and it weeped slightly. I re-drained the radiator at the right side lower plug, removed the shroud and fan, disconnected the upper and lower hoses from the thermostat, RTV'd the mating surface exactly like in the photo here, and no more leaks....

Yeah, how do you know it's 10nm?? My bently doesn't have the torque values listed!!! It only says engine block drain plug and radiator drain plug...

On the m3 model which is a completely different setup, it states 10nm. So can someone clarify what the torque value is for the 4 thermostat bolts? I am halfway through this DIY and am waiting on torque values before buttoning up. Please let me know